In some conventional chain saws, it is known to provide a prefilter and a main air filter. The prefilter has the task of filtering out coarse particles of dirt even before they reach the main air filter. The prefilter is located in a recess of a cover closing off the carburetor body, or what is known as the carburetor cover. The main air filter is located inside the carburetor casing or the housing of the handle of the chain saw and is secured by means of threaded fasteners. This known embodiment has the disadvantage that the prefilter and the main air filter are embodied and disposed as two separate parts. For cleaning the filter, the cover with the prefilter must first be removed. Then the main air filter has to be unscrewed from the housing.
When cleaning operations are done, it repeatedly happens that the user devotes his primary attention only to the cleaning of the main air filter, setting the cover with the prefilter attached thereto aside and paying no attention to it, and so does not clean it; furthermore, he may even lay the prefilter on the ground, so that it becomes contaminated with dirt, clay, leaves or the like, so that despite the cleaning of the main air filter, the filtering effect when the motor-driven tool is put back together again remains greatly impaired because the prefilter is still dirty. When the chain saw is used continuously, for instance, during forestry work, daily cleaning of the filter is prescribed because the output of the internal combustion engine is dependent on the degree of cleanliness of the filter. This means that if the user forgets to clean the prefilter, there are considerable losses in engine capacity. A further disadvantage is that overall disassembly, cleaning and reassembly of the individual separate filters is inconvenient. Furthermore, manufacture is labor-intensive and costly because the prefilter and the main air filter must be manufactured as separate parts and must be provided with separate fastenings.